[GRASS-user] Converting polygons to lines

GRASS GRASS user
1

I need to convert a road network in polygons to lines to do a network analysis.
I converted polygons to line by using v.type.bl- converting boundaries to lines. Then instead of getting single lines, i'm getting border lines over the polygon that was there earlier (No polygon its now line data). I tried cleaning options in GRASS but it didnt work.
Please provide me with guidelines on how to convert it to line data enabling to do network analysis.

Thanks
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2

Well, if roads are polygons it colud be a problem.

if you don't need atributes of roads I sugest to convert polygons to raster, run r.thin, and convert raster to lines. But in that way you will lost road attributes.

supunmali pisze:

I need to convert a road network in polygons to lines to do a network analysis.
I converted polygons to line by using v.type.bl- converting boundaries to lines. Then instead of getting single lines, i'm getting border lines over the polygon that was there earlier (No polygon its now line data). I tried cleaning options in GRASS but it didnt work.
Please provide me with guidelines on how to convert it to line data enabling to do network analysis.

Thanks
  

3

Is that mean it is not possible?? I need the attribute data to do network analysis (e.g. optimal path). Pls suggest a method.

Well, if roads are polygons it colud be a problem.

if you don't need atributes of roads I sugest to convert polygons to
raster, run r.thin, and convert raster to lines. But in that way you
will lost road attributes.

supunmali pisze:

I need to convert a road network in polygons to lines to do a network analysis.
I converted polygons to line by using v.type.bl- converting boundaries to lines. Then instead of getting single lines, i'm getting border lines over the polygon that was there earlier (No polygon its now line data). I tried cleaning options in GRASS but it didnt work.
Please provide me with guidelines on how to convert it to line data enabling to do network analysis.

Thanks
  

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